ASan support for the Zone

src/zone.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 86 matching lines @@
   // and freeing every segment except the one we wish to keep.
   for (Segment* current = segment_head_; current != NULL; ) {
     Segment* next = current->next();
     if (keep == NULL && current->size() <= kMaximumKeptSegmentSize) {
       // Unlink the segment we wish to keep from the list.
       keep = current;
       keep->clear_next();
     } else {
       int size = current->size();
 #ifdef DEBUG
+      // Un-poison first so the zapping doesn't trigger ASan complaints.
+      ASAN_UNPOISON_MEMORY_REGION(current, size);
       // Zap the entire current segment (including the header).
       memset(current, kZapDeadByte, size);
 #endif
       DeleteSegment(current, size);
     }
     current = next;
   }
 
   // If we have found a segment we want to keep, we must recompute the
   // variables 'position' and 'limit' to prepare for future allocate
   // attempts. Otherwise, we must clear the position and limit to
   // force a new segment to be allocated on demand.
   if (keep != NULL) {
     Address start = keep->start();
     position_ = RoundUp(start, kAlignment);
     limit_ = keep->end();
+    // Un-poison so we can re-use the segment later.
+    ASAN_UNPOISON_MEMORY_REGION(start, keep->capacity());
 #ifdef DEBUG
     // Zap the contents of the kept segment (but not the header).
     memset(start, kZapDeadByte, keep->capacity());
 #endif
   } else {
     position_ = limit_ = 0;
   }
 
   // Update the head segment to be the kept segment (if any).
   segment_head_ = keep;
 }
 
 
 void Zone::DeleteKeptSegment() {
 #ifdef DEBUG
   // Constant byte value used for zapping dead memory in debug mode.
   static const unsigned char kZapDeadByte = 0xcd;
 #endif
 
   ASSERT(segment_head_ == NULL || segment_head_->next() == NULL);
   if (segment_head_ != NULL) {
     int size = segment_head_->size();
 #ifdef DEBUG
+    // Un-poison first so the zapping doesn't trigger ASan complaints.
+    ASAN_UNPOISON_MEMORY_REGION(segment_head_, size);
     // Zap the entire kept segment (including the header).
     memset(segment_head_, kZapDeadByte, size);
 #endif
     DeleteSegment(segment_head_, size);
     segment_head_ = NULL;
   }
 
   ASSERT(segment_bytes_allocated_ == 0);
 }
 
@@ skipping 70 matching lines @@
     V8::FatalProcessOutOfMemory("Zone");
     return NULL;
   }
   limit_ = segment->end();
   ASSERT(position_ <= limit_);
   return result;
 }
 
 
 } }  // namespace v8::internal